Particle dispersion problem?

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  01 January 2007
Particle dispersion problem?

hey guys this is my first project with particles i am working on doing a dispersion to my logo but i having a little problem. I am rendering just particles but i would have to increase my amount of particles immensly to fill up the geometry of my logo so it looks like geometry and not like little dots. So is there any way that i can have my actuall geometry turn into particles or would i have to render them seperatly geometry and particles?
  01 January 2007
a very common (and smart) way of doing it is by using an animated gradient as an opacity map and use a birth texture (pflow tools box 1) to emit particles based on the gradient... so the particles will only be born as the logo or object starts to disappear, so you can get away with less particles, rather than having it fill up the object, and have it disperse with many more particles than needed.
  01 January 2007
ok sounds complicating but i am getting it, but how would i make the logo dissapear as the particles come in?
  01 January 2007
This was the same thing i was doing a month's ago. You have to put a gradient map in opacity of your logo and then animate the gradient colors with black and white to animate the disappearence of the logo while particles start emitting.
  01 January 2007
oh ok and also animate an opacity map to your particles Correct?
  01 January 2007
OK, I am having an issue quite close to this, so I will just continue here.

I have the same sort of set up, where particles are being introduced by opacity, determined by an animated gradient ramp.
All works fine, until...
I need to use an opacity map in the object's material.

Multi/Sub object on my mesh. Channel1 has diffuse map and animated gradient ramp in opacity slot, Chanel 2 has an instance of the gradient ramp in its opacity, and is assigned in the Particle View->Position Object operator, density by opacity.

If I replace the opacity map in Channel 1 for the opacity map my material needs, it won't disapear.

I can't use an SDeflector or something to generate the particles, because then they will start off at the top of the mesh which is transparent.
I can't use that in conjunction with a VolSelect and a delete modifier on the mesh because of the very irregular shape of the opacity map.

Is there a simple trick to get around this?
Render on the Amazon Cloud
  01 January 2007
n/m I got figured out what I need.

In this case, the opacity map slot gets a mix map.
Slot one gets an alphs map of the diffuse, slot two gets the animated gradient, and the mix channel gets an instance of slot 1.
Render on the Amazon Cloud
  01 January 2007
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